by Richard Wolf, USA TODAY

by Richard Wolf, USA TODAY

WASHINGTON -- Cellphones and smartphones generally cannot be searched by police without a warrant during arrests, the Supreme Court ruled unanimously Wednesday in a major victory for privacy rights.

Ruling on two cases from California and Massachusetts, the justices acknowledged both a right to privacy and a need to investigate crimes. But they came down squarely on the side of privacy rights.

"Modern cell phones, as a category, implicate privacy concerns far beyond those implicated by the search of a cigarette pack, a wallet or a purse," Chief Justice John Roberts wrote for the court.

"We cannot deny that our decision today will have an impact on the ability of law enforcement to combat crime," he said. "Privacy comes at a cost."

The justices struck down an extensive smartphone search in California that had been upheld by the state Court of Appeals, as well as a more limited probe of an old flip-top cellphone in Massachusetts that a federal judge had thrown out.

Currently, police can search a person under arrest and whatever physical items are within reach to find weapons and preserve evidence that might be destroyed. But the justices noted that vast amounts of sensitive data on modern smartphones raise privacy concerns that differentiate them from other items.

To liken physical objects to digital data, as federal and state government officials did in justifying cellphone searches, Roberts said, "is like saying a ride on horseback is materially indistinguishable from a flight to the moon. Both are ways of getting from point A to point B, but little else justifies lumping them together."

Roberts said police still can examine "the physical aspects of a phone to ensure that it will not be used as a weapon." But once secured, he said, "data on the phone can endanger no one" and the arrested person will not be able to "delete incriminating data."

Justice Department spokeswoman Ellen Canale said prosecutors and police still will "make use of whatever technology is available to preserve evidence on cellphones while seeking a warrant.... Our commitment to vigorously enforcing the criminal laws and protecting the public while respecting the privacy interests protected by the Fourth Amendment is unwavering."

In the past two years, the court has ruled that police can swab a suspect's cheek for DNA to put into an unsolved crimes database, as well as conduct strip searches of prisoners without reasonable suspicion.

But the justices also have said police need a warrant to attach a GPS device to a suspect's car, to obtain blood from a drunken driver who refuses a breathalyzer test, and to bring a drug-sniffing dog up to the door of a suspect's house.

The cellphone cases may be just a precursor to more expansive and potentially explosive high court inquiries. Among them: an examination of the National Security Agency's phone and computer surveillance methods, on which two federal district courts recently diverged.

Privacy advocates hailed the ruling. "By recognizing that the digital revolution has transformed our expectations of privacy, today's decision is itself revolutionary and will help to protect the privacy rights of all Americans," said Steven Shapiro, national legal director of the American Civil Liberties Union.

The two cellphone cases, heard back-to-back in April, involved different crimes, different responses and different lower-court rulings. What joined them was the fact that police searched cellphones without first obtaining warrants.

A California court upheld David Riley's conviction on gang-related weapons offenses that police uncovered after stopping his car for expired tags, finding guns under the hood and then discovering incriminating photos and video on his smartphone. The justices overturned that ruling.

In Massachusetts, a federal appeals court threw out Brima Wurie's conviction after a specifically targeted search of his old-fashioned flip-phone following a street arrest led police to find a cache of drugs and weapons at his home. The high court upheld that ruling.

Because the California search was extensive and the Massachusetts search aimed only at incoming calls and addresses, both cases had appeared ripe for reversal. But with appeals courts divided on the issue of cellphone searches, the justices also were being asked to devise bright-line rules for police to follow - something Roberts emphasized in his opinion.

That's particularly true because technology is advancing, creating new Fourth Amendment puzzles for police to solve. Nine in 10 adults in the U.S. own cellphones, more than half of them smartphones. Eight in 10 use those phones to send text messages; more than half send or receive e-mail, download applications or access the Internet.

Cellphones "are now such a pervasive and insistent part of daily life that the proverbial visitor from Mars might conclude they were an important feature of human anatomy," the chief justice said.

"The phrase, 'There's an app for that' is now part of the popular lexicon," he said. "The average smartphone user has installed 33 apps, which together can form a revealing montage of the user's life."